Circuit breaker



p 1954 J. A. DROBNEY Er AL 2,689,285

cmcun BREAKER Filed Feb. 7, 1952 Fig.3. Y s: s9 WITNESSES: 4 INVENTORS II Il/I/I/ A jaw H 65 3 Joseph A.Drobney 7 g 45 4\ g? H|llerD.Dorfmon.

w x 6 m\ 67 .&aaa=\ W 2| ATTORNE ticular in the appended claims.

Patented Sept. 14, 1954 "UNITED STATES PATENT OFF ICE CIRCUIT BREAKER Joseph A.,Drobney, Duquesne, and HillerD. Dorfman, Beaver, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application February 7, 1952, Serial.:No -:2.70,402

12 Claims. 1

This invention relates to circuit breakers and more particularly :tocircuit breakers which are manually operable ,to open and close the circuit and which .are automatically operated to open the circuit in response to abnormal circuit conditions.

Aniobject of the inventionis to p vi a cu'itxbreaker embodyinga bimetallic switch member whiohris .releasably held in :the closed position by a support member having one end releasabl-y engaging an operating handle.

.Another :object of the invention is to provide a circuit breaker wherein a floating support member formsan operating connection between :a breaker "operating handle and a bimetallic switch :arm.

Another object of :the invention is to provide a circuit breaker .:having a solid current path through the breaker with-no braided or laminated flexible connectors or sliding current-carrying joints.

Another object of the invention is to provide a small, compact circuit breaker which is-of simple construction, reliable in operation and inexpensive to manufacture.

, The novelieatures that are considered characteristic of the invention are set forth in par- The invention itself, both as to construction and operation, to-

;gether with additional objects and advantages thereof, will be best understood .irom the following detailed description thereof when read in .aconjunction'with the accompanying drawing.

In said drawing:

Figure 1 is an elevational view, partly in sec- ..tion and with the cover removed, of a circuit breaker embodying the principles of the invention.

Fig. 2 is a view similar to Fig. 1 but-showing the breaker in the tripped open position.

Fig. 3 is a fragmentarysectional view taken substantially along line III.III of Fig. 1 and looking in thedirectionof the arrows.

Referring to the drawing, the circuit breaker comprises .a casing .II [and a cooperating cover plate I3 (a fragmentof .which is shown in Fig. 3) .bothof insulatingmaterial. Astationary contact I5 ismounted on aresilient terminal member ll of conducting material .which extends through .an opening in one .end wall of the casing I I and has ,a terminal connectorsuchas a screw 19 at its outer end. TA movable switch member or arm -:'2| constructedof bimetallic material is secured atone-end totheinnenend of a resilient terminal member;.23-.whichrextends throughan opening in the other end wall of thecasing II andhas a erminalconn ct rsuchasa screw 5 i outer end. The switch member 21 at its other end car- ,ries a mohfiblepOHtactZI for cooperating with the stationary contact I5. The switch member 2| is normally biased open by the normal bias of the resilient terminal ,member 23 on which it is mounted. Insteadoi usinga resilient member 23 the resilience of the switch member 2| may be used iori biasing the contacts open.

An operating ,handle 3| of molded insulating material has opposed trunnions ,33 molded integral therewith which engage in suitable bearing openings in .the side wall of thecasing .I I and in the coverplate I3 to pivotally mount the handle. The handle 3| extends outwardly through an opening 37 in the .casing II. Theinner end of the handle 3i provided with a projection 39 having a-surface 41 which, in the closed position of the breakenrcleasably engages the rounded upper end of ,a support member .43. The sup- ,port 1member ,43 has an angular portion 45 the end of which normally .engages the bimetallic switch member 2i to releasably restrain the switch member in. clo sed;position. The support member A3 is provided with a pair of spaced ears .4? (only one being shown) formed-at right angles thereto and havingelongated slots 49 thereon through whichextends a pin 5i suitably supported in the side wall of the casing I I and in the cover plate I3. Aspringfiiihaving one end connected to the supportmember Aland the other end adjustablygsecured to a member bymeans of a screw 5.? biases thesupport member 143 in a clockwise direction about the pin 15 I A U -shaped magnet yoke '59 (Figs. 1, 2 and '3) is provided with projecting ends 5i engaging in ope'ningsin the side wall of the casing II and the cover [3 '(as clearly shown in Fig. 3) to rigidly support the magnet yoke. An armature "63 is rigidly mountedon the bimetallic switch member 21. The'legs of the U-shaped magnet yoke areprovide'd withsloping pole faces'fiii which cooperate with corresponding sloping faces 6'! on thearmature'fit. -The sloping faces are arranged to permit one of themagnetic members to move into the others. "This has the advantage that the air .gap is small but permits a relative large movement'betweenthe two magnetic members.

In the closed position pf the breaker the upper end of the upport member .43 bears against the projectionjton the qperating handle tl and the rounded end of the portion 4,5 .of the support member bears against .the bimetallic switch arm ,2 I. One component of the bias -on ;the ,switch zmember tends {to .turn :the support member 43 upwardly and another component tends to rotate the support member 43 counterclockwise about the pin In the closed position the upward component is restrained by the engagement of the end of the support member 43 with the projection 39 or the handle and the bias of the spring 53 is suflicient to hold the switch arm 2| in the closed position against the component tending to rotate the support member 43. In order to manually open the contacts |5-2'|, the operating handle 3| is rotated clockwise from the full line position to the oil position shown by dot and dash lines (Fig. 1). This movement of the handle causes the projection 39 on the handle to release the support member 43 whereupon the biasing force of the resilient member 23 moves the switch member 2| to the open position and, aided by the spring 53 moves the support member longitudinally to the position shown by dot and dash lines at 43a in Fig. l.

The contacts are closed by reverse movement of the handle 3| from the off position to the on position. During this movement of the handle 3| a cam surface 69 on the projection 39 engages the upper end of support member 43 and cams this member downwardly to move the switch arm 2| to the closed position.

The high expansion side of the bimetallic switch member 2| is on the lower side so that when the bimetal is heated in response to overload currents the contact end of the bimetal element bends upwardly. Consequently, when the bimetal element is heated in response to overload currents below a predetermined value of, for instance, ten times normal rated current, the bimetal element bends upwardly causing counterclockwise rotation of the support member 43 about the pin 5|. During the early part of this movement of the support member 43, the handle 3| rotates clockwise until the end of the support member 43 slips off of the surface 4| thereon. As soon as the support member 43 is disengaged from the projection 39 of the handle the biasing force of the spring 23 as of the bimetal element 2| moves the support member 43 upwardly to the left of the projection 39 and the spring 53 rotates the support member slightly clockwise. This results in restoring the handle to its on position.

During the early part of the tripping movement and until the support member 43 is disengaged from the projection, the contacts are maintained closed by the resilient spring member II which causes the stationary contact I5 to follow in engagement with the movable contact until the support member 43 slips ofi of the surface 4| on the handle projection 39. At this time the contacts are opened with a snap action.

Should the handle be held in the closed position during the occurrence of an overload current, the force of the thermal binding of the bimetal element 2| would overcome the function between the rounded upper end. of the support member 43 and the surface 4| on the handle projection 39 and cause counter-clockwise rotation of the support member until the support member is disengaged from the handle. The switch member would then move to the open position with a snap action.

In the closed position of the breaker where the handle opposes the upward component of the force on support member 43, the spring 53 has suflicient force to maintain the support member in the position shown in full lines in Fig. 1 against the normal bias of the resilient member 23.

. 4 With the parts in the position shown in Fig. 2, however, the spring 53 alone is unable to overcome the bias of the resilient member 23 and move the parts to the closed position.

In order to close the contacts following an automatic opening operation, it is necessary to move the handle 3| in a clockwise direction from the position as shown in Fig. 2 to the off" position indicated in Fig. 1. This movement of the handle causes the projection 39 to move over to the left of the support member to the position shown by dot and dash lines in Fig. 1, whereupon the spring 53 moves the support member 43 to the position shown in dot and dash lines in Fig. l. The switch member 2| is then moved to the closed position by counter-clockwise movement of the handle back to the on position at which time the cam surface 69 engages the end of the support member 43 and cams it downwardly to move the switch member 2| to the closed position.

The circuit breaker is opened instantaneously in response to overload currents above the predetermined value of, for instance, ten times normal rated current or short circuit currents by means of the electromagnet 5933. Upon the occurrence of such an overload or short circuit current, the electromagnet is energized by the current flowing in the bimetallic switch member 2| and the fixed magnet yoke 59 attracts the armature 53 instantaneously moving the bimetallic switch member 2| to the open position. This movement of the switch member 2| causes counter-clockwise movement of the support member 43 and release of the support member from the handle 3|. The parts then assume the positions in which they are shown in Fig. 2.

The contacts are closed following an electromagnetic opening operation in the previously described manner by first moving the handle 3| to the reset position and then :to the on position.

The invention provides a circuit breaker of simple and rugged construction having a minimum number of parts which are mounted in the casing by merely laying the parts in grooves 0r recesses in the casing and without the use of any frame other than the casing itself. Thebreaker has a solid current path therethrough without the use of flexible conductors. Th bimetallic switch member acts to trip the breaker open after a time delay and electromagnetic means is provided to instantaneously trip the breaker. The circuit breaker is trip-free of the operating handle.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details and arrangement of parts thereof may be made without departing from some of the essential features of the invention.

We claim as our invention:

1. A circuit breaker comprising a stationary contact, a switch member of bimetallic material biased open and movable to open and close the circuit, means resiliently mounting one end of said switch member, a movable contact on the other end of said bimetallic switch member for cooperating with said stationary contact, an operating handle movable to an open position and to a closed position, a support member disposed between said handle and said bimetallic switch member for normally restraining said switch member in closed position, fixed means mounting said support member for pivotal and longitudinal movement, and said bimetallic switch member bending in responseftoov'erload currents to cause pivotal movement of said support member about said fixed support means to a position to permit opening movement'of said switch member free-of said'handle.

2. A circuit breaker comprising a stationary contact, a switch member or bimetallic material movable to open and close the "circuit, resilient means mounting one end of said switch member and biasing said switch member to open position, a movable co'nta'c'ton the other end of said bimetallic switch member for cooperating with said stationary-contact, an operating handle movable to an open position and to 'a'close'd position, a support member 'releasably engaging said handle'anden'gagin'g said bimetallic switch member, fixed means mounting said support member, said support member being mounted for pivotal and longitudinal movement about "said fixed mounting "means, movement of said handle to said been position permitting longitudinal movement of said "support member to permitsaidre'sih ierit means to move saidbimetallic switch membert'o open position, and thermal bending of said bimetallic switch member causing pivotal and longitudinal movement "of said support member aboutsaid fif ie'd means to permit said resilient means to move said bimetallic switch member to ripen position.

3. A circuit breaker comprising stationary contact means, a bimetallic "switch member biased open and movableto open and close the circuit, fixedly mounted resilient means mounting one end of said switch member, movable contact means onthe other end of said bimetallic switch member for cooperating with said stationary contact means, an'operatinghandle 'mov'able to an open position and to 'a closed position, a support member between said handle and said bimetallic switch member normally restraining said switch member in closed position, movement of said handle to open position releasing said support member from said handle to permit movement of said'support member to one position to permit opening movement of said bime'ta'llic switch membar, and thermal bending of said bimetallic switch member in response 'to overload currentspivotally moving said Support member to another position to effect opening movement of said switch member free of said handle.

4. A circuit breaker comprising a stationary contact'a switch member of bimetallic material biased open and movable 'to open and close the circuit, a movable contact on said bimetallic switch member for cooperating with said stationary contact, an operating handle movable to an open positi'o'n'and'to a 'close'd'position, a support member disposed between said handle and said bimetallic switch member'for norm'allyr'estrainin'gsaid switch member in closed position, said handle releasably engaging said "support mmber, fixed means mounting said support member for pivotal and longitudinal movement, movement of said handle to said open position efiecting longitudinal movement of said support member to permit opening movement of said bimetallic switch member, :and thermal bending of said bimetallic switch member pivotally moving said support member about said fixed mounting means to permit opening movement of said bimetallic switch member free of said handle,

5. A circuit breaker comprising a stationary 6,, coo eratin with sai stationar contact, an cp crating handle movable to an open position and to a closed position to effect opening and closing movement of said bimetallic switch member, a support member having one end engaging sa-i'd bimetallic switch member and the other end releasably engaging said handle for normally restraining said bimetallic-switch member in closed position, said handle when moved to said open position effecting release of said support member from said handle to *permit movement-of said bimetallic switch member to open position, thermal bending of said bimetallic switch member in response to overload currents 'below a predetermined value pivotally moving said support m'ember to 'a position to permit opening movement of said bimetallic switch member, electroresponsive means comprising a fixedly mounted magnet yoke and an armature mounted on said bimetallic switch member to be energized by currents flowing in said "bimetallic switch member, and said electroresponsive means being operable when energized by overload currents above said predetermined value to instantaneously move said support member and permit movement of said bi metallic switch member to said open position.

6. A circuit breaker comprising a bimetallic switch member biased to open position and movable to open and close the circuit, an operating handle movable to an open position and to a closed position, 'a support member-engaging said operating handle and said bimetallic switch member, fixed means mounting said support member for pivotal and longitudinal movement, biasing means biasing said support member to "a position where it normally restrains said bimetallic switch member in closedpositiommo'vement of said operating handle to said open position permitting longitudinal movement of said support member to permitcpening'movement of said bimetallic switch member, and thermal bending 'of said bimetallic switch member pivotally moving said support member about said flxed mounting means and against the bias of said biasing means to permit opening movement of said bimetallic switch member.

7. A circuit breaker comprising a bimetallic switch member biased-to "open'position andmovable to open and'close the circuit, an operating handle movable to an open position and to a closed position, a supportmember engaging said operating handle and said bimetallic switch member, means mounting said "support member for pivotal and longitudinal movement, biasing means biasing said-support member'to a position where it-normally restrains said'bime'tallic switch member, in closed position, "movement of said operatinghandle to'said open positi'on'permitting longitudinal movement of said support member and opening movement of said bimetallic switch member, and thermal bending of said bimetallic switch member pivotally moving "said support 'member'against *the bias of said biasing means to permit opening "movement of said bimetallic switch member, and adjusting means for adjusting said biasing means to vary the thermal tripping point of said breaker.

8. A circuit breaker comprising a bimetallic switch member biased open and movable to open and close the circuit, an operating handle movable to an open position and to a closed position, a support member engaging said operating handle and said bimetallic switch member, means mounting said support member for pivotal and longitudinal movement, biasing means biasing said support member to a position to normally restrain said bimetallic switch member in closed position, movement of said operating handle effecting longitudinal movement of said support member to permit opening movement of said bimetallic switch member, thermal bending of said bimetallic switch member in response to overload currents below a predetermined value causing pivotal movement of said support member against the normal bias of said biasing means to permit opening movement of said bimetallic switch member free of said handle, adjusting means for adjusting said biasing means to vary the thermal tripping point of said bimetallic switch member, and electroresponsive means operable in response to overload currents above said predetermined value to cause pivotal movement of said support member and instantaneous movement of said bimetallic switch member to open position.

9. A circuit breaker comprising a stationary contact, a bimetallic switch member movable to open and close the circuit, a movable contact on one end of said bimetallic switch member cooperating with said stationary contact, resilient means mounting the other end of said bimetallic switch member and biasing said bimetallic switch member in opening direction, an operating handle movable to an open position and to a closed position, a support member having one end releasably engaging said handle and the other end engaging said bimetallic switch member, spring means biasing said support member to a predetermined position to normally hold said bimetallic switch member in closed position, said resilient means in said predetermined position of said support member biasing said bimetallic switch member about said support member to provide contact pressure, movement of said handle to the open position releasing said support member and causing movement of said support member to one position to permit said resilient means to move said bimetallic switch member to open position, and thermal bending of said bimetallic switch member pivotally moving said support member to another position to permit said resilient means to move said himetallic switch member to the open position.

10. A circuit breaker comprising a stationary contact, a bimetallic switch member having a movable contact on one end thereof and movable to open and close the circuit, resilient means mounting the other end of said bimetallic switch member and biasing said switch member in opening direction, an operating handle movable to an open position and to a closed position, a support member having one end engaging said bimetallic switch member and the other end releasably engaging said handle to normally restrain said bimetallic switch member in closed position, said resilient means in the closed position of said breaker biasing said bimetallic switch member about said one end of said support member to provide contact pressure, and thermal bending of said bimetallic switch member disengaging said support member from said handle and moving said support member and said handle to a position to permit said biasing means to move said bimetallic switch member to open position free of said handle.

11. A circuit breaker comprising a stationary contact, a switch member of bimetallic material biased open and movable to open and close the circuit, a movable contact on said bimetallic switch member for cooperating with said stationary contact, an operating handle movable to an open position andto a closed position, a support member releasably engaging said handle and engagingsaid bimetallic switch member for normally restraining said switch member in closed position, fixedly mounted means supporting said support member for pivotal and longitudinal movement, said bimetallic switch member bending in response to overload currents to pivotally move said support member about said fixedly mounted means and disengage said support member from said handle to permit opening movement of said switch member free of said handle, and resilient means supporting said stationary contact to maintain said stationary contact in engagement with said movable contact during thermal bending of said bimetallic switch member and until said support member is released from said handle.

12. A circuit breaker comprising a stationary contact, a bimetallic switch member biased open and movable to open and close the circuit, a movable contact on said bimetallic switch member for cooperating with said stationary contact, an operating handle movable to an open position and to a closed position, a support member disposed between said handle and said bimetallic switch member and releasably engaging said handle for normally restraining said switch member in closed position, movement of said handle to said open position effecting longitudinal movement of said support member to permit opening movement of said bimetallic switch member, thermal bending of said bimetallic switch member pivotally moving said support member and disengaging said support member from said handle to permit opening movement of said bimetallic switch member free of said handle, and resilient means supporting said stationary contact to maintain said stationary contact in engagement with said movable contact at least during thermal bending of said himetallic switch member.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,203,462 Frank June 4, 1940 2,520,873 Bean Aug. 29, 1950 2,534,938 Woodward Dec. 19, 1950 2,636,958 Dorfman et a1. Apr. 28, 1953 

